Failure Notification in a Network Having Serially Connected Nodes

1. A link state protocol controlled Ethernet network having data plane multicast capability, the network comprising: a first node configured to issue a frame containing a control message signifying a local topology change, the frame being addressed to a control plane specific multicast group address; a second node configured: to receive the frame containing the control message; to perform a reverse path forwarding check on the frame to determine if the frame arrived at the second node on a port expected for multicast frames issued by the first node; to discard the frame immediately when the frame fails the reverse path forwarding check; and when the frame passes the reverse path forwarding check: if the second node is two-connected between two nodes and the frame has been received from one of the two nodes, forwarding the frame to the other of the two nodes; and if the second node is more than two-connected, processing the frame in the control plane before forwarding the frame to another node.

2. The link state protocol controlled Ethernet network of claim 1 , wherein the control message is a link state routing protocol control message.

3. The link state protocol controlled Ethernet network of claim 1 , wherein the control plane specific multicast group address is a source specific multicast address.

4. The link state protocol controlled Ethernet network of claim 1 , wherein the second node is configured to select a plurality of downstream nodes to which the frame is to be forwarded using a shortest path tree rooted on the first node.

5. The link state protocol controlled Ethernet network of claim 1 , wherein the control plane specific multicast group address is a (*,G) multicast address common to all nodes and assigned to control message exchange.

6. The link state protocol controlled Ethernet network of claim 1 , wherein the second node is configured to acknowledge the frame to a first node when the frame passes the reverse path forwarding check.

7. The link state protocol controlled Ethernet network of claim 6 , wherein the second node is configured to acknowledge the frame to the first node only when the second node is two-connected between the first node and a third node.

8. A node for a link state protocol controlled Ethernet network having a data plane multicast capability, the node comprising: a routing element configured to receive a frame containing a control message signifying a local topology change, the frame being issued by a first other node of the network and being addressed to a control plane specific multicast group address; and a reverse path forwarding check element configured: to perform a reverse path forwarding check on the frame to determine if the frame arrived at the node on a port expected for multicast frames issued by the first other node; to discard the frame immediately when the frame fails the reverse path forwarding check; and when the frame passes the reverse path forwarding check: when the second node is two-connected between two nodes and the frame has been received from one of the two nodes, to forward the frame to the other of the two nodes; and when the second node is more than two-connected, to process the frame in the control plane before forwarding the frame to another node.

9. The node of claim 8 , wherein the control message is a link state routing protocol control message.

10. The node of claim 8 , wherein the control plane specific multicast group address is a source specific multicast address.

11. The node of claim 8 , configured to select a plurality of downstream nodes to which the frame is forwarded using a shortest path tree rooted on the first other node.

12. The node of claim 8 , wherein the control plane specific multicast group address is a (*,G) multicast address common to all nodes and assigned to control message exchange.

13. The node of claim 8 , configured to acknowledge the frame to the first other node when the frame passes the reverse path forwarding check.

14. The link state protocol controlled Ethernet network of claim 13 , configured to acknowledge the frame to the first other node only when the node is two-connected between the first other node and a second other node.

15. A method of operating a node for a link state protocol controlled Ethernet network having a data plane multicast capability, the method comprising: receiving a frame containing a control message signifying a local topology change, the frame being issued by a first other node of the network and being addressed to a control plane specific multicast group address; and performing a reverse path forwarding check on the frame to determine if the frame arrived at the second node on a port expected for multicast frames issued by the first other node; discarding the frame immediately when the frame fails the reverse path forwarding check; and when the frame passes the reverse path forwarding check: if the second node is two-connected between two nodes and the frame has been received from one of the two nodes, forwarding the frame to the other of the two nodes; and if the second node is more than two-connected, processing the frame in the control plane before forwarding the frame to another node.

16. The method of claim 15 , wherein the control message is a link state routing protocol control message.

17. The method of claim 15 , wherein the control plane specific multicast group address is a source specific multicast address.

18. The method of claim 15 , comprising selecting a plurality of downstream nodes to which the frame is forwarded using a shortest path tree rooted on the first other node.

19. The method of claim 15 , wherein the control plane specific multicast group address is a (*,G) multicast address common to all nodes and assigned to control message exchange.

20. The method of claim 15 , comprising acknowledging the frame to the first other node when the frame passes the reverse path forwarding check.

21. The method of claim 20 , comprising acknowledging the frame to the first other node only when the node is two-connected between the first other node and a second other node.